Google may lag behind its two biggest rivals in the public cloud, but Urs Hölzle, the technology titan's senior vice president for technical infrastructure, sees Google's cloud revenue eclipsing its ad business in five years.

"I think cloud will actually turn out to be a huge business because it's a service business," he said during an interview on stage at the Structure conference in San Francisco on Wednesday.

Asked what he would say to enterprises that are skeptical about using Google's cloud, Hölzle pointed to the company's long track record providing enterprise services through its Apps productivity suite, and through the Google Search Appliance, which it's been selling to enterprises since 2002.

Businesses may not think of Google first for their cloud applications, but Hölzle said that's based on an outdated perception of the company. While he wouldn't say what Google has up its sleeve, he said forthcoming announcements will show that Google is committed to the enterprise.

One advantage for Google is that it has to invest in hyperscale technologies to power its own vast consumer services (you know, the ones that are monetized by ads) and that innovation trickles down to its enterprise cloud offerings. But both Amazon and Microsoft also build out systems to run their core businesses.

Right now, Google is trying to attract new customers by competing on price. Hölzle's comments came the same day the company announced a new feature that lets developers configure their own compute instances, so they don't pay for more processing power and memory that their application needs.

It remains to be seen if moves like that will attract more businesses to the Google Cloud Platform, or if the company will remain in third place in the public cloud.

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